2001 GS500 Carburetor Leak Troubleshooting Help (Fuel Mixture Adjusting Screw?)

Started by roxxer69, April 21, 2019, 03:18:08 PM

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roxxer69

First, I apologize for creating a new thread and not just updating the last one. I thought this was going to be a separate topic but evolved into a continuation of the last.

Anyway, here's the issue with my 2001 GS500:
Before starting my bike for the first time this year, I noticed my left carb was/is leaking gas from a particular location (I think it's the fuel mixture adjuster screw).   [See Image URL] https://imgur.com/a/7VBY5bz  A decent size pool of gas settles on the starter cover and the part highlighted in the image shows where there is some gas residue. I believe this is the Fuel Mixture Screw.

I then started the bike from cold and she ran rough at first. The choke was on as usual, but RPMs struggled to hit 2K even with full choke. There was also white vapor/smoke out of the exhaust, a significant amount, not just your average water vapor. She would stall out if I did not have constant throttle, and this continued to happen for about a minute or so. I then cut the power and decided to take a look at the carbs.
No other external leaks are detected, and all other gaskets and jets look good. After I put the bike back together, she ran like a champ with the choke working normally, causing the bike to cold start at 5K RPMs until warmed up. I took a ride, everything was wonderful. (Would this be because I emptied the excess fuel from the carb?) Skip forward a couple of days and BOOM, the same issue happened. Gas leaked in the same place, choke struggling to reach 2K RPMs, and white smoke. Warming her up eventually solves all issues, but as you may have guessed, the issue keeps reoccurring.

Using this forum to help troubleshoot (Thanks Macka), I changed the oil and noticed fuel seemed to overflow into the old oil because when I changed it it smelt like gas. I think this is what caused the white vapor/smoke. At this point, again thanks to the help from users on this forum, I thought the issue may be with the float needle not working properly, or maybe it was left on "prime," I don't remember if that was the case. Either way, I think it is safe to say that something is causing too much fuel to continuously fill the left carb, and it only happens when the bike is sitting. (Does this seem like a correct assumption?)

Just to restate, no other leaks are detected, bike runs good after the initial low RPM choke and white smoke fiasco. No other issues once it's warmed up i.e. she idles at 1.2K, accelerates fine, no stalling, no leaks as it is running, only when it's been sitting for a couple days.


To sum up:
1. Looking at the picture https://imgur.com/a/7VBY5bz is the red arrow pointing to the fuel mixture adjuster? Just want to make sure. It doesn't seem like I am able to remove the metal plug that is in that cylinder, is it stripped? Any suggestions?
2. Gas seemed to have leaked into the oil, would this indicate left carb overflow, possibly a float needle issue? Would this cause the startup issues?
3. If it is in fact fuel overflow because of a faulty needle, is it normal to leak from the fuel mixture adjuster? Or will this need to be replaced as well?

Thank you all again for the help, this forum kicks ass.


mr72

how many threads does it take to do this? I can't even find my initial response on this issue, did you delete the thread?

It's a bad o-ring on the pilot mixture needle, all other o-rings are probably bad as well, follow my guide and make your life better. 18 year old carbs that haven't been redone will need attention. Let's hope you didn't put carb cleaner on/in the carbs without them stripped all the way to bare metal, but expect to replace every rubber part with the possible exception of the diaphragms if you've kept them away from carb cleaner. And that includes the intake boot o-rings (not inside the carbs).

The answers are all here:

https://joshkarnes.blogspot.com/2017/09/fixing-common-gs500-carburetor-issues.html

roxxer69

Yeah, I apologized for the extra thread, as stated this thread was supposed to be different but it evolved into a continuation of the previous one...and I couldn't find a way to delete the thread so...

Anyway, I got your post (on both threads...sorry)

I usually strip carbs before cleaning them, so I think the 18 year old rings are just starting to go on their own. I will be changing the o-rings.

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